May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Corneal Refractive Index Changes in Keratoconus
J. Schallhorn; M. Tang; Y. Li; D. Huang
Author Affiliations & Notes
  • J. Schallhorn
    USC Keck School of Medicine, Los Angeles, California
  • M. Tang
    Ophthalmology-USC, Doheny Eye Institute, Los Angeles, California
  • Y. Li
    Ophthalmology-USC, Doheny Eye Institute, Los Angeles, California
  • D. Huang
    Ophthalmology-USC, Doheny Eye Institute, Los Angeles, California
  • Footnotes
    Commercial Relationships  J. Schallhorn, None; M. Tang, Optovue, Inc., F; Optovue, Inc., P; Y. Li, None; D. Huang, Optovue, Inc., R; Optovue, Inc., F; Optovue, Inc., I; Optovue, Inc., C; Carl Zeiss Meditec, Inc., P; Optovue, Inc., P.
  • Footnotes
    Support  NIH grants R01 EY018184-01, P30 EY03040; Research to Prevent Blindness; Optovue, Inc.
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 4345. doi:https://doi.org/
  • Views
  • Share
  • Tools
    • Alerts
      User Alerts
      You are adding an alert for:
      Corneal Refractive Index Changes in Keratoconus
      You will receive an email whenever this article is corrected, updated, or cited in the literature. You can manage this and all other alerts in My Account
      The alert will be sent to:
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation
      Citation

      J. Schallhorn, M. Tang, Y. Li, D. Huang; Corneal Refractive Index Changes in Keratoconus. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4345. doi: https://doi.org/.

      Download citation file:

      © ARVO (1962-2015); The Authors (2016-present)

      ×
    • Get Permissions
  • Supplements
Abstract

Purpose: : To study the effect of keratoconus on the corneal index using optical coherence tomography (OCT) and Orbscan.

Methods: : 12 eyes of 8 patients with keratoconus and 25 eyes of 16 normal patients were imaged using the Orbscan slit-scanning device and the Visante OCT device. The central corneal thickness was measured with both instruments and the ratio was calculated. According to optical principles, the apparent corneal thickness measured by OCT scales in direct proportion to the group index and the apparent corneal thickness measured by slit-scanning scales inversely with the refractive index.

Results: : The ratio of the OCT/Orbscan central pachymetry in normal eyes is 0.986 ±0.030 and the ratio in keratoconic eyes is 1.011±0.034. The two are significantly different from each other (p=0.042). Assuming the group and refractive indices changes equally, keratoconus increase index by 1.3% on the average.

Conclusions: : Keratoconus appears to increase the corneal index. One possible mechanism is increased corneal stress and strain due to the ectasia. This might lead to more tightly packed collagen lamellae and higher refractive and group indices.

Keywords: keratoconus • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • cornea: stroma and keratocytes 
© 2008, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2015 Association for Research in Vision and Ophthalmology.
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×
This site uses cookies. By continuing to use our website, you are agreeing to our privacy policy.Accept